PRENATAL GROWTH OF THE PIG 



LAWSON G. LOVVREY 



Pi'ofessor of Anatomy in the University of Utah 

 From the Anatomical Laboratory of the University of Missouri 



FIVE FIGURES 



Numerous observations on various phases of growth are to be 

 found in the biological literature. Most of those concerning 

 prenatal growth are upon the human embryo, although scattered 

 observations are also recorded on other mammals, and a few on 

 the lower vertebrates. The work presented in this paper was 

 done in the attempt to trace, in the pig, the course of the prenatal 

 growth of the body and especially the relative growth of the vari- 

 ous organs. The results are also compared with the course of 

 growth in the human species and in the lower vertebrates, so far 

 as data are available, The work was done in the Anatomical 

 Laboratory of the University of Missouri, under the direction of 

 Dr. C. M. Jackson, to whom I am deeply indebted for his inter- 

 est, aid and valuable suggestions. 



MATERIAL AND METHODS 



The material used for this paper consists of 22 litters of pig 

 embryos, comprising about 130 individuals, of which number 

 105 were used. In most cases, all the pigs of the litter were used, 

 in the others, three or four specimens about the average of the 

 litter were studied. These litters of embryos were secured from 

 the packing houses in Chicago (August 31, 1909), Kansas City 

 (December 27, 1909), and Columbia (at various times, spring 

 1910). Wherever possible, the litters were worked up in a fresh 

 condition. In the other cases, they were preserved in a 5 per 

 cent aqueous solution of formalin for varying lengths of time 

 (table 1). 



THE AMERICAN JOURNAL OF ANATOMY, VOL. 12, NO. 2 

 SEPTEMBER, 1911 



107 



